Dynamic corrections for a non-linear touchscreen

• US 7,180,508 B2
• Filed: 09/17/2002
• Issued: 02/20/2007
• Est. Priority Date: 09/17/2002
• Status: Expired due to Fees

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Tyco Electronics Corporation (TE Connectivity Ltd. (United Kingdom))
• Inventors: Kent, Joel C., Aroyan, James L.
• Primary Examiner(s): CHANG, KENT WU
• Application Number:
  US10/246,059
• Publication Number:
  US 20040061687A1
• Time in Patent Office: 1,617 Days
• Field of Search: 345/173, 345/178, 178/18.01, 178/17.02, 178/18.02
• US Class Current: 345/178
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0444 using a single conductive element covering the whole sensing surface, e.g. by sensing the electrical current flowing at the corners
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

The present invention provides a way to measure and track non-linear corrections in touchscreens. Some or all of the relevant non-linear corrections may be determined automatically. Production floor test equipment may make electronic measurements, compute parameters, and load the parameters in non-volatile memory of the controller electronics. Alternatively, the controller electronics can make the electronic measurements and determine non-linear parameters. The latter embodiment of the invention permits the determination of non-linear parameters in the field, dynamically tracking changes in the non-linear characteristics of installed touchscreens that occur over time or due to environmental conditions.

Claims

1. A touchscreen system for generating touch coordinates comprising:

a touchscreen which generates (a) measurable information indicative of a given electrical characteristic in the touchscreen in the absence of a touch and (b) touch information in response to a touch;

a correction-parameter circuit in communication with the touchscreen, wherein the correction-parameter circuit receives the measurable information and generates a non-linear correction parameter; and

a correction-application circuit which receives the touch information and the non-linear correction parameter and corrects for non-linearity in the touchscreen.

2. The touchscreen system of claim 1, wherein the touchscreen further comprises a substrate having four corners and a corner contact at each corner.

3. The touchscreen system of claim 2, wherein the touchscreen is one of a five-wire touchscreen, a nine-wire touchscreen, or a capacitive touchscreen.

4. The touchscreen system of claim 2, wherein the substrate further comprises an interior region having a first resistivity ρ

_A and an exterior region having a second resistivity PB, wherein the first and second resistivities ρ

_A, ρ

_B are not equal.

5. The touchscreen of claim 2, wherein the substrate further comprises an interior region and an exterior region, wherein the exterior region borders and surrounds the interior region.

6. The touchscreen of claim 5, wherein the interior region further comprises deletion lines.

7. The touchscreen system of claim 1, wherein the touchscreen further comprises a substrate having a first coating, wherein the first coating does not uniformly cover the substrate.

8. The touchscreen system of claim 7, wherein the first coating comprises a plurality of strips made of a first material, and wherein the substrate further comprises a gap in between each pair of strips.

9. The touchscreen system of claim 1, wherein the correction-parameter circuit generates a correction parameter having a value and the correction-application circuit uses the value for the correction parameter to correct for non-linearity in the touchscreen.

10. The touchscreen system of claim 1, wherein the correction-application circuit periodically receives the touch information and the non-linear correction parameter and periodically corrects for non-linearity in the touchscreen.

11. A touchscreen system for generating signals representing a touch position comprising:

a substrate having four corners and a corner contact at each corner;

a digitizing circuit in communication with each corner contact, wherein the digitizing circuit measures an electrical characteristic of one contact in the absence of a touch and generates measurable information in response; and

a correction-parameter circuit in communication with the digitizing circuit, wherein the correction-parameter circuit generates a non-linear correction parameter.

12. The touchscreen system of claim 11, wherein the electrical characteristic is one of a resistance, a capacitance, a voltage, or a current.

13. The touchscreen of claim 11, wherein a first voltage at one corner contact is measured as a second voltage is applied to at least one of the remaining corner contacts.

14. The touchscreen of claim 13, wherein the second voltage is applied to two remaining corner contacts while a third voltage is applied to one remaining corner contact.

15. The touchscreen system of claim 11, further comprising a sheet spaced from the substrate, wherein the sheet comprises a second coating and the substrate comprises a first coating, and wherein the second coating faces the first coating.

16. The touchscreen of claim 11, further comprising a correction-application circuit which receives touch information from the digitizing circuit and the non-linear correction parameter from the correction-parameter circuit, and corrects for non-linearity in the touchscreen.

17. The touchscreen system of claim 16, wherein the correction-parameter circuit determines a resistivity ratio based upon the measurable information, and the correction-application circuit corrects for a non-linearity in the touchscreen system based upon the resistivity ratio.

18. The touchscreen system of claim 11, wherein the digitizing circuit periodically measures the electrical characteristic and periodically generates measurable information in response.

19. A method for correcting non-linearities in a touchscreen, wherein the touchscreen includes a first point spaced apart from a second point, the method comprising:

measuring an electrical characteristic of the first point in the absence of a touch while applying one of a voltage or current to the second point;

generating measurable information in response; and

correcting for non-linearity in the touchscreen system using the measurable information.

20. The method of claim 19, wherein the electrical characteristic is one of a voltage, a current, a resistance, or a capacitance.

21. The method of claim 19, further comprising periodically correcting for non-linearity in the touchscreen system using the measurable information.

22. The method of claim 19, further comprising manually correcting for non-linearity in the touchscreen system using the measurable information.

23. The method of claim 19 further comprises generating a non-linear correction parameter using the measurable information.

24. A touchscreen system for generating signals representing a touch position comprising:

a substrate including a first contact spaced apart from a second contact and a first coating overlying the substrate and in communication with the first and second contacts;

a sheet spaced from the substrate, wherein the sheet includes a second coating facing the first coating, wherein the sheet is movable from a first position, in which the second coating is not in contact with the first coating, to a second position, in which the second coating is in contact with the first coating;

a digitizing circuit in communication with both the first and the second contacts, wherein the digitizing circuit receives first analog measurable information in the absence of a touch and generates digital measurable information in response, and wherein the digitizing circuit receives the analog measurable information when the sheet is in the first position;

a correction-parameter circuit in communication with the digitizing circuit, wherein the correction-parameter circuit receives the digital measurable information and generates a correction parameter in response; and

a correction-application circuit which receives the correction parameter and corrects for non-linearity in the touchscreen system using the correction parameter.

25. The touchscreen system of claim 24, wherein the substrate includes a third contact spaced apart from a fourth contact.

26. The touchscreen system of claim 25, wherein the digitizing circuit is in communication with both the third and the fourth contacts, and wherein the digitizing circuit receives second analog measurable information and generates digital measurable information in response.

27. A method for correcting non-linearities in a touchscreen, wherein the touchscreen comprises a substrate and a sheet spaced from the substrate, the substrate including a first contact spaced apart from a second contact and a first coating overlying the substrate and in communication with the first and second contacts, the sheet including a second coating facing the first coating, wherein the sheet is movable from a first position, in which the second coating is not in contact with the first coating, to a second position, in which the second coating is in contact with the first coating, the method comprising:

measuring an electrical characteristic of the first contact in the absence of a touch, while applying one of a voltage or current to the second point, when the sheet is in the first position;

generating measurable information in response to the measuring; and

correcting for a non-linearity in the touchscreen system using the measurable information.

28. The method of claim 27, wherein the correcting for a non-linearity is periodically performed on the touchscreen.

29. A touchscreen system for generating signals representing a touch position comprising:

a touchscreen;

a digitizing circuit in communication with the touchscreen, wherein the digitizing circuit receives analog measurable information in the absence of a touch and generates digital measurable information in response; and

a correction-parameter circuit in communication with the digitizing circuit, wherein the correction-parameter circuit corrects for a non-linearity in the touchscreen using the digital measurable information.

30. A method for correcting non-linearities in a touchscreen, the method comprising:

measuring an electrical characteristic of the touchscreen in the absence of a touch, wherein the electrical characteristic has a value; and

correcting for a non-linearity in the touchscreen system using the value for the electrical characteristic.

31. The method of claim 30 wherein the correcting for the non-linearity is performed dynamically.

32. The method of claim 30 wherein the correcting for the non-linearity is performed using production floor test equipment.

33. The method of claim 30 wherein the correcting for the non-linearity is performed using controller electronics.